In the given problem, the ith letter of the alphabet is substituted by the two-digit ith prime number.

For example, we know that the 4th letter of the alphabet is "D",and 4th prime number is 7, which becomes 07 when written as a two digit number with leading zero. Similarly, the letter "E" will represent the letter "11"

Thus, the word "83190271" is broken down to four 3-digit numbers 83, 19, 02 and 71. Replacing these by their letter equivalents, we obtain "WHAT".

Proceeding similarly, we obtain the required secret message as:

"WHAT IS THE FIFTIETH PRIME NUMBER?"

In terms of the Sieve of Eratosthenes, We can easily determine that "229" is the 50th prime number.

Accordingly, the proper response to the above query would be "229" which is "Two Hundred Twenty Nine" when spelled out, and thus will be encoded as "718347 19734307611107 718311437197 43234311"

Thus, the required answer is either "229", or "718347 19734307611107 718311437197 43234311"